INT 15 - DESQview - QEXT.SYS - INSTALLATION CHECK

	AX = 11DEh
Return: CF clear if installed
	    AX = segment at which QEXT.SYS is located
Desc:	QEXT.SYS is Quarterdeck's HMA manager for DESQview; more recent
	  versions also implement the XMS standard
Note:	a private entry point (see #00434) may be found by searching the
	  beginning of the returned segment for the signature string
	  "QUARTERDECK EXTENDED MEMORY MANAGER 286"; the word immediately
	  prior to the signature contains the QEXT version number in BCD,
	  and the word prior to that contains the offset within the QEXT
	  code segment of the private entry point
SeeAlso: INT 2F/AX=4310h"XMS",INT 67/AH=3Fh